java9.lang

Class Iterables

java.lang.Object

java9.lang.Iterables

public final class Iterables
extends Object

A place for static default implementations of the new Java 8 default interface methods and static interface methods in the Iterable interface (and also for removeIf from Collection).

Method Summary

Modifier and Type	Method and Description
static <T> void	forEach(Iterable<? extends T> it, Consumer<? super T> action) Performs the given action for each element of the passed Iterable until all elements have been processed or the action throws an exception.
static <T> boolean	removeIf(Iterable<? extends T> it, Predicate<? super T> filter) Removes all of the elements of the passed Iterable that satisfy the given predicate.
static <T> Spliterator<T>	spliterator(Iterable<? extends T> it) Creates a Spliterator over the elements described by this Iterable.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

forEach

public static <T> void forEach(Iterable<? extends T> it,
                               Consumer<? super T> action)

Performs the given action for each element of the passed Iterable until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller.

The behavior of this method is unspecified if the action performs side-effects that modify the underlying source of elements, unless an overriding class has specified a concurrent modification policy.

Implementation Requirements:

The default implementation behaves as if:

     for (T t : this)
         action.accept(t);
 

Type Parameters:

T - the type of elements of the Iterable

Parameters:

it - the Iterable to call forEach on

action - The action to be performed for each element

Throws:

NullPointerException - if one of the specified it or action arguments is null

Since:

1.8

removeIf

public static <T> boolean removeIf(Iterable<? extends T> it,
                                   Predicate<? super T> filter)

Removes all of the elements of the passed Iterable that satisfy the given predicate. Errors or runtime exceptions thrown during iteration or by the predicate are relayed to the caller.

Implementation Requirements:
The default implementation traverses all elements of the Iterable using its Iterable.iterator(). Each matching element is removed using Iterator.remove(). If the Iterable's iterator does not support removal then an UnsupportedOperationException will be thrown on the first matching element.

Type Parameters:

T - the type of elements of the Iterable

Parameters:

it - the Iterable to call removeIf on

filter - a predicate which returns true for elements to be removed

Returns:

true if any elements were removed

Throws:

NullPointerException - if one of the specified it or filter arguments is null

UnsupportedOperationException - if elements cannot be removed from the passed Iterable. Implementations may throw this exception if a matching element cannot be removed or if, in general, removal is not supported.

spliterator

public static <T> Spliterator<T> spliterator(Iterable<? extends T> it)

Creates a Spliterator over the elements described by this Iterable.

Implementation Note: If the passed Iterable is an instance of Collection the implementation delegates to Spliterators.spliterator(java.util.Collection) so it is effectively the same as calling

     Spliterators.spliterator((Collection<T>) it);
 

Implementation Note: If the passed Iterable is not an instance of Collection this implementation creates an early-binding spliterator from the iterable's Iterator. The spliterator inherits the fail-fast properties of the iterable's iterator. The spliterator returned for non-Collection sources has poor splitting capabilities, is unsized, and does not report any spliterator characteristics. Implementing classes could nearly always provide a better implementation.

Type Parameters:

T - the type of elements of the Iterable.

Parameters:

it - the Iterable for which the Spliterator should be created.

Returns:

a Spliterator over the elements described by the passed Iterable.

Since:

1.8